1. Field of the Invention
The present invention relates to a sensor device, and a portable communication terminal and electronic device using the sensor device.
2. Description of the Related Art
In recent years, proximity sensors that monitors changes in capacitance have been proposed as sensors for detecting the proximity of an object (see, for example, International Publication No. 2004/059343). These capacitance detection sensors can detect the proximity of an object without contacting it.
However, conventional proximity sensors as disclosed in International Publication No. 2004/059343 basically detect the proximity of all objects. Accordingly, they are not suitable for detecting a particular detection target. For instance, to detect the opening/closing of a lid or door, the proximity of only the lid or door should be detected. Actually, however, conventional sensors detect other objects besides the lid or door.
As described above, it is difficult for conventional proximity sensors to reliably detect only a particular detection target.